The Vedic hymns themselves have a lot to do with the gods helping the Aryas against the Dasus (a word referring to both demons and the Dravidian aboriginals of the subcontinent). So, at least in that sense, the Vedas are not particularly universalist.

“Would the gods of the Eddas permit their followers to cooperate with the gods of the Vedas?”

From a certain point of view, they’re the same gods. The gods of both pantheons go back to the pantheon of the Proto-Indo-European religion. As such, one-to-one correlations can be drawn between the gods in each pantheon: Odin and Varuna, Tyr and Mitra, Thor and Indra, etc. This is accepted practice in the study of Indo-European comparative religion, for instance in the works od Dumézil, Puhvel, and others.

That said, gods are best understood within their own cultural context, I think. It doesn’t make much sense for, say, Germans to practice Hinduism when they have their own (admittedly, and unfortunately, less well-known) religious heritage, and their own gods.

“So – this Benoist fellow – what spirits does he deal with?”

As much as I enjoy deBenoist’s writing, I think his sort of “non-religious paganism” is problematic. The majority of people will never approach matters of truth and meaning through philosophical speculation (as useful as that may be to those who are capable), but rather through myth and ritual, as they always have. Collin Cleary presents an interesting critique of deBenoist’s thinking (especially of his “On Being a Pagan”) in TYR vol. 3, in the essay “Paganism Without Gods”.

and furthermore:

As I say below, ancient paganism has very strong totemic, ancestral themes running through it. I’d recommend reading Ancient City by Numa Denis Fustel de Coulanges.

Regarding Germanic paganism, there is good reason to believe that the Kobolds were originally ancestral gods like the Roman Manes. And regarding the more major gods, early Germanic aristocracy claimed descent from Odin (tracing their lineages to the Vǫlsungs to Odin). Even the Christian Bede traces these genealogies of some of the early Anglo-Saxons. Thus, in both instances, you have examples of ancestor worship — they not only worshiped these gods but believed they were descended from them.